Contemporary sensorless AC drives require the use of electromechanical quantities estimation. The skin effect occurring in AC machines with solid secondary or with solid secondary elements causes machines of this type to be represented by equivalent circuits containing distributed elements, which makes the analysis of machine electrodynamic states more complicated and hinders the construction of relatively simple and effective estimators of electromechanical quantities. The variability of rotor parameters is modelled, with a good approximation, by the machine secondary multi-loop equivalent circuit with lumped elements. In this paper the construction procedure of electromechanical state variable estimators basing on this type of equivalent circuit will be presented. The simulation investigations of the created electromechanical quantities estimators, performed for the selected states of solid iron rotor AC machine operation will be shown as well.
Accurate force and torque calculations are fundamental to being able to predict the operation of an electromechanical device or system. The Maxwell stress tensor and the virtual work principle are the two major theories for force and torque calculation. However, if local distributions of torque are needed to couple to structural and vibration analyses, the conventional Maxwell stress approach cannot provide this easily. A recently developed approach based on sensitivity analysis has the capability to deliver local stress and torque as well as accurate global results. In addition, this approach divides the total torque into different components which are essential to the design of electrical devices. This paper includes several numerical examples of torque calculations of different electrical machines. The results are verified by a commercial software package using the Maxwell stress based force calculation.
The paper presents a methodology for the optimization of a Brushless Direct Current motor (BLDC). In particular it is focused on multiobjective optimization using a genetic algorithm (GA) developed in Matlab/Optimization Toolbox coupled with Maxwell from ANSYS. Optimization process was divided into two steps. The aim of the first one was to maximize the RMS torque value and to minimize the mass. The second part of the optimization process was to minimize the cogging torque by selecting proper magnet angle. The paper presents the methodology and capabilities of scripting methods rather than specific optimization results for the applied geometry.
An analysis of the influence of inverter PWM speed control methods on the operation of a brushless DC (BLDC) motor was carried out. Field-circuit models of the BLDC motor were developed taking into account rotational speed control by two classic methods: the unipolar H_ON_L_PWM and the bipolar H_PWM_L_PWM. Waveforms of the electrical and mechanical quantities and the motor parameters were computed. The results of the computations were verified by measurements performed on a specially designed test stand. On the basis of the measuredwaveforms of the electrical and mechanical quantities the dependence of the drive system efficiencies and power losses on rotational speed was determined for the two methods of inverter control.
This document contains results of research on complex motion common magnetic circuit electromagnetic converter characteristic that allows making independent axial and rotary shaft motion. The converter in addition to linear-rotary mechanism consists of two drive rotors and one common magnetic circuit excitator. Such a solution allows to reduce volume of the machine and makes it easier to use. The paper cites design intent and possible structure of the device. Phenomenon of common magnetic circuit adverse effect on correct operation of device is discussed. The concept of using relative error as a way to evaluate the influence of that phenomenon in the torques is discussed. Waveforms of determined relative errors for all possible cases is presented. Furthermore the concept of average relative error is defined and its use as a quantitative method of assessing the degree of common circuit impact is indicated. Definition of relative error ripple factor is given, and its usage is shown. Winding inductance calculation based on free FEM application is shown and its influence on control strategy and power system.
The article presents the results of diagnostic measurements of partial discharge signal propagation from the winding insulation in electrical machinery, which were performed using an on-line method. This paper describes the results of experiments and the acquired experience in the monitoring of winding insulation in high power and high voltage electrical machines which are important in industrial production processes. The authors show the measurement techniques employed in their research. Representative measurement results are presented along with their analysis. The authors use an SKF monitoring systems to measure: vibrations, temperature, and humidity, as major factors affecting partial discharge activity in the from winding insulation of electrical machines.
This paper presents the concept of an innovative field-controlled axial-flux permanent-magnet (FCAFPM) machine. In order to show the working principle and features of the proposed dual-rotor with surface-mounted PM’s and iron poles, a toroidallywounded slotted single-stator FCAFPM machine is investigated and analyzed in detail, using 3-D FEAnalysis. The control range, back electromotive force (back-EMF), output and cogging torque components have been evaluated.